PROJECT SUMMARY/RESEARCH ABSTRACT Severe traumatic injury carries significant morbidity, mortality and costs, especially considering the increasing burden of morbidity posed by our rapidly aging population. Progress in traumatic resuscitation and critical care support over the past 30 years has led to improvements in survival after severe injury. However, the burden of poor outcomes after severe trauma in the aged has been shifting from early deaths from refractory multi-organ failure (MOF) to a syndrome characterized by a prolonged course of chronic critical illness (CCI), with persistent low-grade organ dysfunction, disposition to long-term acute care and skilled nursing facilities, and dismal long-term outcomes. In many instances, previously functional individuals develop a post-injury baseline state of cognitive, physiologic and functional morbidities consistent with the frailty syndrome of the elderly. We describe this emerging phenotype of an acute, persistent, injury-associated decline in health status as ?induced frailty?. The inflammatory trigger of severe trauma produces both a cytokine and genomic ?storm? of the innate immune response early after injury that is highly predictive of complicated outcomes and post-injury mortality. It is not known whether persistence of this aberrant immunological response persists among survivors of CCI after trauma, nor whether it is associated with poor long-term outcomes. Our overarching hypothesis is that persistent inflammation and protein muscle wasting after severe trauma leads inevitably to induced frailty, decreased mobility and function, is associated with dismal long-term outcomes in older adults. We have developed this initial prospective, observational study in order to further determine the incidence and natural history of this morbid phenotype in severely injured older adults.